We propose to establish a Confocal Microscopy Core facility to serve diverse biomedical researchers at the Mount Sinai School of Medicine. The proposed facility would house a Leica confocal laser scanning microscope (CLSM) with a confocal fluorescence unit, and a Silicon Graphics workstation with Voxel View image analysis software. The broad range of projects proposed by the initial user group (eight laboratories in six departments) is representative of a larger group of potential users of confocal microscopy. Each research proposal utilizes the confocal's ability to visualize fluorescent probes in fixed tissue, to focus through thick sections or cell layers, to execute a through focus series and/or to perform 3-D reconstruction. The Cell Biology and Anatomy Department (CB/A) has allocated departmental space for the CLSM within its microscopy facility. Institutional support includes leasing expenses and salary for the Core director. The Confocal Facility Director will oversee the day-to-day maintenance and operation of the facility. The advisory committee includes faculty who have expertise in light microscopy and electronic data processing. This facility will provide a significant new technology for Mount Sinai and most directly for the participants, seven of whom have current NIH support and all of whom have collected data demonstrating feasibility and need for their proposed uses of the CLSM. This facility will fill a major void at Mount Sinai where there is essentially no confocal microscope available; the single confocal microscope is dedicated to the research of its owner.